Intestinal anti-inflammatory effects of RGD-functionalized silk fibroin nanoparticles in trinitrobenzenesulfonic acid-induced experimental colitis in rats

Abstract

Background

Current treatment of inflammatory bowel disease is based on the use of immunosuppressants or anti-inflammatory drugs, which are characterized by important side effects that can limit their use. Previous research has been performed by administering these drugs as nanoparticles that target the ulcerated intestinal regions and increase their bioavailability. It has been reported that silk fibroin can act as a drug carrier and shows anti-inflammatory properties.

Purpose

This study was designed to enhance the interaction of the silk fibroin nanoparticles (SFNs) with the injured intestinal tissue by functionalizing them with the peptide motif RGD (arginine–glycine–aspartic acid) and to evaluate the intestinal anti-inflammatory properties of these RGD-functionalized silk fibroin nanoparticles (RGD-SFNs) in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis.

Materials and methods

SFNs were prepared by nanoprecipitation in methanol, and the linear RGD peptide was linked to SFNs using glutaraldehyde as the crosslinker. The SFNs (1 mg/rat) and RGD-SFNs (1 mg/rat) were administered intrarectally to TNBS-induced colitic rats for 7 days.

Results

The SFN treatments ameliorated the colonic damage, reduced neutrophil infiltration, and improved the compromised oxidative status of the colon. However, only the rats treated with RGD-SFNs showed a significant reduction in the expression of different pro-inflammatory cytokines (interleukin [IL]-1β, IL-6, and IL-12) and inducible nitric oxide synthase in comparison with the TNBS control group. Moreover, the expression of both cytokine-induced neutrophil chemoattractant-1 and monocyte chemotactic protein-1 was significantly diminished by the RGD-SFN treatment. However, both treatments improved the intestinal wall integrity by increasing the gene expression of some of its markers (trefoil factor-3 and mucins).

Conclusion

SFNs displayed intestinal anti-inflammatory properties in the TNBS model of colitis in rats, which were improved by functionalization with the RGD peptide.

Keywords:

• nanoparticles
• inflammatory bowel disease
• silk fibroin
• TNBS rat colitis
• RGD

Acknowledgments

This work was supported by the Junta de Andalucia (P10-AGR-6826 and CTS 164) and the Spanish Ministry of Economy and Competitiveness (AGL2015-67995-C3-3-R) with funds from the European Union, Fondo Social de la DGA (grupos DGA), Ministerio de la Economía y Competitividad del Gobierno de España for the public funding of Proyectos I+D+I – Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad (SAF2014-54763-C2-2-R), and CASEN-RECORDATI S.A. A Rodriguez-Nogales and F Algieri are postdoctoral fellows of the University of Granada; AA Lozano-Perez’s research contract is partially supported (80%) by the FEDER/ERDF Program of the Region of Murcia 2014–2020 (FEDER 14-20-01). ME Rodriguez-Cabezas is a postdoctoral fellow of CIBER-EHD. The CIBER-EHD is funded by the Instituto de Salud Carlos III. We thank SD Aznar-Cervantes, for his technical assistance in the production of SFNs, and N Garrido-Mesa and MP Utrilla, for their contributions to the in vivo biological evaluation of the effect of SFNs.

Author contributions

All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.